Question

1. define a variable and write an equation for each situation. then solve. susans cell - phone plan allows her to use 950 minutes per month with no additional charge. she has 188 minutes left for this month. how many minutes has she already used this month? 21. in the fifth year of operation, the profit of a company was 3 times the profit it earned in the first year of operation. if its profit was $114,000 in the fifth year of operation, what was the profit in the first year? 22. solve each equation. check your answer. - 9x = 48 23. \\(\frac{n}{7}=2 + 11\\)

Explanation:

20.

Step1: Define the variable

Let $x$ be the number of minutes Susan has used this month.

Step2: Write the equation

The total number of minutes allowed is 950 and the number of minutes left is 188. So the equation is $x + 188=950$.

Step3: Solve the equation

Subtract 188 from both sides of the equation: $x=950 - 188$.
$x = 762$.

Step1: Define the variable

Let $p$ be the profit in the first - year of operation.

Step2: Write the equation

The profit in the fifth year is 3 times the profit in the first year and the profit in the fifth year is $114000$. So the equation is $3p=114000$.

Step3: Solve the equation

Divide both sides of the equation by 3: $p=\frac{114000}{3}$.
$p = 38000$.

Step1: Solve the equation

We have the equation $-9x = 48$. Divide both sides by - 9.
$x=\frac{48}{-9}=-\frac{16}{3}=- 5\frac{1}{3}$.

Step2: Check the answer

Substitute $x =-\frac{16}{3}$ into the original equation: $-9\times(-\frac{16}{3})$.
$-9\times(-\frac{16}{3})=48$, which is the right - hand side of the original equation.

Answer:

Susan has used 762 minutes this month.

21.